Transitional currents of spin-1/2 particles
Russian Federation State Scientific Center ‘A.I. Alikhanov Institute of Theoretical and Experimental Physics’, ul. Bolshaya Cheremushkinskaya 25, Moscow, 117259, Russian Federation
The problem of constructing explicitly covariant representations for transitional currents of spin-1/2 particles is solved for both the nonrelativistic theory and the relativistic theory with massive particles. In the massless case, such representations exist only for transitional currents that are nondiagonal in helicity. The diagonal currents have algebraic representations that are not explicitly covariant.